Like the title says, what are the widest tires that you can fit on the rear of a stock impala? I already am running 275's on the rear on the stock rims, but I'm looking to upgrade to 20's on all 4 corners and I want to run the widest tire possible on the rear without notching the frame. So I guess my final question is, what width wheel, backspacing, offset, etc. to run the widest tire on the back?

Thanks for all the input. This should help out, along with the stickies in the beginning of the page.

That said, I run 1 1/2" widened oem wheels and 315/35 on my BBB. FTR I'm sure everyone knows;
1. Caprice/9C1 do not use exactly the same axle as the SS
2. And my SS setup will NOT bolt to my FWB as the rear is either narrower, or, the frame is slightly wider.